This invention relates to a resealable pressure vent for a container and more particularly for venting a battery container.
In the manufacture of rechargeable batteries, especially nickel cadmium cells, a safety vent is generally provided to release any abnormal pressure which might develop in the cell during charging or abuse of the battery.
Vents for battery cells are known and fall into two main categories, "one-time" or "resealable". The "one-time" vent is of simple design and comprises weakened areas in the battery casing, when the internal gas pressure in the battery reaches a predetermined venting pressure, the weakened area is punctured thereby protecting the battery from exploding.
The main disadvantage of the "one-time" design is that once the vent is punctured, the interior of the battery becomes exposed to the atmosphere and the battery quickly dries up or fails because of carbonation. Of the two, the preferred safety vent is the "resealable" design.
The "resealable" vent is generally provided with an elastic element such as a spring or a rubber ball which will release the excess pressure inside the battery. Furthermore, after the excess pressure is released, the elastic element recovers its original state or form and reseals the battery. The battery continues to function although possibly at a slightly deteriorated rating.